The invention relates to a method and system for remote monitoring of a carbon adsorption process for the treatment of a contaminated fluid stream.
The Clean Air Act Amendment of 1990 (CAAA) requires efficient and economical control strategies for disposal of volatile organic compounds (VOCs). VOCs are carbon compounds that react with nitrogen oxides and other airborne chemicals in the presence of sunlight to form ozone, a primary component of smog. Under the CAAA, thousands of unregulated sources are required to reduce or eliminate VOC emissions. In addition, sources that are currently regulated will need to meet stricter regulatory requirements such as the maximum achievable control technology (MACT) requirements in Title III of the CAAA.
Carbon adsorption is a process for controlling VOC emissions. In the chemical process industry, granular activated carbon is used for water and wastewater treatment applications. An adsorption isotherm evaluation can provide useful information for designing a carbon bed unit. The evaluation can provide information on adsorpability of specific VOCs, equilibrium capacity estimates and changes in adsorption capacity relative to VOC concentration. Dynamic adsorption testing can provide other necessary design data, including required contact times and breakthrough curve. A breakthrough curve is the VOC concentration exiting the bed over time as the carbon""s capacity for the VOC is reduced. In industrial and groundwater treatment applications, single-stage adsorption is commonly encountered, despite the fact that two-stage systems could permit a first carbon bed to approach saturation to obtain full carbon use.
Many times, carbon adsorption is one unit operation in an overall treatment scheme comprising several treatment modules. If the water being treated contains suspended solid, or if upstream unit operations include precipitation or settling steps for removal of metals, a separate filtration step is required. Air stripping is another unit operation that can be applied as a pretreatment to carbon adsorption for removal of VOCs. The air stripping can remove the bulk of the VOCs prior to carbon adsorption to extend bed life. Carbon adsorption can be used to treat the off-gas from the air stripper.
In some applications, VOC content of feed to a bed changes significantly over a short period. In these applications, frequent or real-time monitoring would be valuable for providing a basis for redirecting a process feed to a bed with a differing designxe2x80x94a design more effective or efficient for treating the changed feed. Real-time monitoring can also provide a basis for optimizing associated treatment modules to minimize VOC outputs and reduce process variation.
There is a need for a method and system to provide frequent or real-time monitoring to meet regulatory requirements and to adjust the process or associated treatment modules to improve effectiveness and efficiency of an overall carbon adsorption process.
The present invention provides a method to monitor a carbon bed adsorption process in real time and to use the information acquired by such monitoring for optimization and control.
In a first embodiment, the invention is a method of treating a contaminated fluid stream. In the method, a characteristic of a flow of a contaminated fluid stream to a carbon adsorption zone is sensed. The sensing is remotely monitored to determine a treatment for the contaminated fluid stream. The contaminated fluid stream is then treated according to the monitoring.
In another embodiment, the invention is a system for treating a contaminated fluid stream. The system comprises a sensor that senses a characteristic of a flow of a contaminated fluid stream prior to treatment, a monitor to receive information concerning the characteristic from the sensor and to consequently control the carbon adsorption zone to treat the contaminated fluid stream. The monitor is situated at a location remote from the carbon adsorption zone.